Conventional oxygen concentrators often employ a rotary compressor to pump air through the concentrator and to the patient. Such compressors provide a desirably high rate of air flow and do not generate excessive pressures. The typical rotary compressor features carbon vanes that are slidably mounted in generally radial slots in the compressor's rotor. The rotor itself is eccentrically mounted in a chamber formed in the housing of the compressor. An electric motor drives the rotor such that centrifugal force urges the carbon vanes outwardly from their slots to engage the wall of the chamber. The vanes form successive compartments that collect air that is introduced into the compressor. As the vanes rotate, the air is moved into a gradually constricted portion of the chamber where it is compressed. This compressed air is then delivered through an exhaust port to the concentrator's filter.
Conventional carbon vane rotary compressors exhibit at least a couple of significant problems. As each vane slides back and forth within its respective slot, a considerable amount of heat is generated. Moreover, the friction resulting from such sliding causes the vanes to wear and generates carbon dust, which can foul the compressor. As a result, these types of compressors required frequent maintenance. In particular, the dust must be removed and the vanes replaced at regular intervals. Moreover, due to the constant wear on the vanes, known rotary compressors are very likely to exhibit gaps between the ends or tips of the vanes and the chamber wall. This can result in air leakage, which may significantly impair the operation of the compressor and the oxygen concentrator.